Medin (Czechia)

This paper evaluates the various approaches to strength and stiffness analysis of fracture osteosynthesis using a headless Herbert screw. The problem has been extensively addressed using several scientific approaches, namely the analytical approach, stochastic approach, experimental approach, and (marginally) using the finite elements method. The problem is illustrated on the use of a prototype headless screw Ti: 4.0/1.4 × 30/7 (manufacturer: Medin, Czech Republic) and the surgical treatment of the fifth metatarsal fracture. Mathematical equations for the analytical calculation of the maximum stresses in the screw were established for tensile/compression loading. This problem is also interesting because of its static indetermination in tension and compression; for this reason, it was necessary to use the deformation condition, i.e., the relationship between screw extension and bone contraction. The stochastic (probabilistic) approach, i.e., application of the Monte Carlo method, takes advantage of the mathematical equations derived during the analytical solution by respecting of the natural variabilities and uncertainties. The analytical and stochastic approaches were validated by measurements on porcine bones and by the finite element method. The data measured experimentally were also processed and used for deriving an equation, appropriately approximating the data. The main part of the measurement was to determine the axial force generated during osteosynthesis with a headless screw. The obtained compressional force was used to determine the maximal stress in the screw and bone. Finally, the methods were compared. In this paper, comprehensive and original approaches based on the authors’ experience with multiple methods are presented. Obtained results are necessary for headless screw designers during optimalization of the implants and are also useful for surgeons developing new surgical techniques. This biomechanical problem was solved in cooperation with the engineering industry and physicians to improve the quality of care for patients with trauma in orthopedics and surgery.

This contribution describes a non-traditional application of the probabilistic approach for the evaluation of implants in biomechanics, trauma surgery, and orthopedics. Particularly, it focuses on the osteosynthesis of the proximal femur (collum femoris). The application of the Winkler elastic foundation as a surrogate for the interaction between the collum femoris and femoral/cancellous screws combined with the Monte Carlo (SBRA) method), seems to be a modern trend in the biomechanical evaluation of implant reliability. Here, we present a biomechanical probabilistic assessment based on mechanical stress and deformation of screws in bone is presented.

Nickel-based austenitic stainless steels are still common for manufacture of implants intended for acute hard tissue reinforcement or stabilization, but the risk of negative reactions due to soluble nickel-rich corrosion products must be considered seriously. Corrosion processes may even be accelerated by the evolution of microstructure caused by excessive heat during machining, etc. Therefore, this study also deals with the investigation of microstructure and microhardness changes near the threaded holes of the anterolateral distal tibial plate containing approx. 14wt.% Ni by composition. There were only insignificant changes of microhardness, grain size, or microstructure orientation found close to the area of machining. In addition, wettability measurements of surface energy demonstrated only minor differences for bulk material and areas close to machining. The cyclic potentiodynamic polarization tests were performed in isotonic physiological solution. The first cycle was used for the determination of corrosion characteristics of the implant after chemical passivation, the second cycle was used to simulate real material behavior under the condition of previous surface damage by excessive pitting corrosion occurring during previous polarization. It was found that the damaged and spontaneously repassived surface showed a three-time higher standard corrosion rate than the “as received” chemically passivated surface. One may conclude that previous surface damage may decrease the lifetime of the implant significantly and increase the amount of nickel-based corrosion products distributed into surrounding tissues.

In the area of musculoskeletal MR images analysis, the image denoising plays an important role in enhancing the spatial image area for further processing. Recent studies have shown that non-local means (NLM) methods appear to be more effective and robust when compared with conventional local statistical filters, including median or average filters, when Rician noise is presented. A significant limitation of NLM is the fact that thy have the tendency to suppress tiny objects, which may represent clinically important information. For this reason, we provide an extensive quantitative and objective analysis of a novel NLM algorithm, taking advantage of pixel and patch similarity information with the optimization procedure for optimal filter parameters selection to demonstrate a higher robustness and effectivity, when comparing with NLM and conventional local means methods, including average and median filters. We provide extensive testing on variable noise generators with dynamical noise intensity to objectively demonstrate the robustness of the method in a noisy environment, which simulates relevant, variable and real conditions. This work also objectively evaluates the potential and benefits of the application of NLM filters in contrast to conventional local-mean filters. The final part of the analysis is focused on the segmentation performance when an NLM filter is applied. This analysis demonstrates a better performance of tissue identification with the application of smoothing procedure under worsening image conditions.

PURPOSE OF THE STUDY Based on the experience with using the Judet plates in stabilization of rib fractures an innovated Judet plate was constructed in cooperation with the Development Department of Medin company. During the preclinical part of the project, following the construction of the new Judet plate, a surgical technique was elaborated. Subsequently, the clinical application of rib osteosynthesis with innovated plates was commenced. MATERIAL AND METHODS In the course of the last three years the innovated Judet rib plate including the instruments were constructed by the Development Department of Medin company in cooperation with the Trauma Centre and the Department of Surgery of the University Hospital Královské Vinohrady. The goal of the innovation was the changes in technical parameters of rib plates which are compared with the new plates of other companies: 1. Adequate plate stability along the rib axis. 2. Creation of fixation clips for a stable, but not traumatized fixation of the plate around the rib. 3. Decreased robustness of the plate with sufficient stiffness. 4. Working out of a new technique of plate fixation with the use of new instruments. 5. Ensuring plate fixation with cortical locking screws. In the preclinical part of the project osteosynthesis of the broken rib was performed with a plate on a chest model for the basic types of rib fractures. Subsequently, the plate was used for rib osteosynthesis in a cadaver. The goal of the new instruments was besides temporarily maintaining the rib fracture reduction also the subsequent temporary application of plates with the assistance of fixation tongs before the final fixation of plates. In 2017, the clinical part of the project on the stabilisation of flail chest with the innovative Judet plates was launched. This type of innovative Judet plates has so far been used in 3 patients. RESULTS As to the surgical technique of ribs osteosynthesis: The profile of the plate has been adapted to the rib profile and can be further adjusted to rib curvature, also the fixation shoulders of the plates have been reshaped. The innovated plate has been complemented with a new configuration of fixation clips and the possibility to fix the plate with locking screws. The used cortical locking screws enable appropriate stabilisation of plates. They were tested on a laboratory model of ribs and on a cadaver using the new set of instruments. The plates can be easily shaped with tongs. The anchorage of fixation clips is adequately provided for also by means of tongs. The plates can be fixed to the rib without any significant compression of intercostal nerves. The essential change of the innovated Judet plate is its weight, which meets the contemporary trends in construction of rib plates designed for anatomical fixation. The first experience with the innovated plates in flail chest injury confirmed the safety of the procedure for stable osteosynthesis of rib fractures. Adequate stability of the chest wall facilitated an early withdrawal of ventilatory support. Osteosynthesis of rib fractures with innovated plates performed in the first three patient was without complications, including in the postoperative period. DISCUSSION A series of prospective studies prove the correctness of the indications of early rib osteosynthesis in flail chest. Further indications for rib osteosynthesis are postinjury chest deformity, dislocation of rib fracture fragments with a lung injury, and malunion of rib fracture. According to these studies the surgical stabilisation of the chest is a safe and efficient method resulting in pain reduction, decrease of ventilatory support time, and also in reduced morbidity. For rib osteosynthesis anatomical plates, Judet plates and intramedullary plates are used. Our innovation of the Judet plate aimed to improve the technical parameters of the plate. The innovative Judet plate means a significant improvement in technical parameters and stands comparison with the plates of others companies, which are used in the Czech Republic. This is also evidenced by preliminary clinical results. CONCLUSIONS Surgical stabilisation of the flail chest segment is considered to be he method of choice in treating selected patients, leading to the improvement of respiratory function and shortening of the ventilatory support time. The new technical parameters of the plate, including its weight, new fixation clips, locking screws and instruments are the priorities of the innovated Judet plates. The innovation of Judet plates represents an important step towards the extension of indications for surgical stabilisation of the chest. Key words:innovative Judet plates, preclinical study, osteosynthesis of rib fractures.

This article reports about the new design of external fixators invented at the VSB - Technical University of Ostrava, Trauma Centre of The University Hospital in Ostrava and MEDIN a.s. These fixators are intended for the treatment of open, unstable and complicated fractures in traumatology and orthopaedics for humans or animals. The new design is based on shape and weight optimalization based on composite materials, application of smart materials, nanotechnology, low x-ray absorption, antibacterial protection, patient’s comfort, reduction in the duration of the surgical treatment, and cost).

At first, the doctors mentioned their own medical experience with treatment of complex pelvic injury in patients with polytrauma and give reasons for necessity of early stabilization of pelvic fractures by means of external fixation, especially with continuous hemorrhage into lesser pelvis region and the retroperitoneum. Afterwards, they used damage control surgery methods including selective embolization. However, this article is focused also on the design of external fixators applied in traumatology and orthopaedics (i.e. skills of engineers). These fixators can be used in the treatment of open and unstable (i.e. complicated) fractures of pelvis and its acetabulum. Two versions (i.e. old and new) are compared. Numerical modelling (i.e. Finite Element Method), together with CAD modelling, experiments, material engineering, and nanotechnology are presented as a support for developing of a new design of external fixators.

Human granulocytic anaplasmosis (HGA) is a tick-borne, acute illness with increasing incidence [1]. It is caused by Anaplasma phagocytophilum proved to have a tick vector Ixodes ricinus in Europe. HGA is usually a mild or even asymptomatic illness with non-specific influenza-like symptoms, and is associated with variable but suggestive laboratory alterations. When comparing HGA with human ehrlichiosis caused by Ehrlichia chaffeensis, beside differences in geographical distribution, there is a close association with higher hospitalization rate (36% vs. 48.6%), morbidity and life-threatening complications (e.g. adult respiratory distress syndrome, disseminated intravascular coagulopathy, meningoencephalitis, renal failure) and mortality (0.6% vs. 1.9%) in E. chaffeensis cases [1]. A rush, as a clinical presentation, is also more frequently reported in patients with E. chaffeensis. HGA occurs in previously healthy individuals, and the disease severity is associated with the degree of compromised immunity of infected patients. The diagnosis is confirmed retrospectively using specific laboratory tests, which include positive polymerase chain reaction (PCR), identification of A. phagocytophilum in a culture of acute-phase blood, or the detection of specific antibodies to A. phagocytophilum in convalescent-phase serum samples. Doxycycline provides rapid and effective treatment.

This Journal of course receives many more papers than it can publish. One large group of rejects deserves some attention, for in rejecting them it must seem that we are failing to encourage enthusiasts, often enthusiasts working whole-heartedly and most profitably for new schools in outlandish places. The pattern is a simple one. A department grows dissatisfied with standard teaching methods, and introduces changes: abandoning formal lectures in favour of small group teaching with detailed programming of the content is a common example, but the variety is great. At the end of the course, an examination shows that the average mark is much higher than in previous years. Sophisticated statistical methods, often designed by a department of statistics and described and tabulated at inordinate length, confirm that the change is highly significant. Conclusion—the new system is proved better than the old! But is it? There was a famous demonstration at the Relay Assembly Test Room of the Hawthorne plant of the Western Electric Company. Changes were made in the conditions of work, such as introducing rest periods at one time, and shorter working hours at another. It became clear it was not the experimental changes that made the girls work more effectively, but the greater interest focussed on them which increased their desire to do well (Roethlisberger & Dickson, 1939). All educational experiment is liable to the Hawthorne effect. The teachers are more interested in what they are teaching: the students react pleasurably to the idea that they are part of a genuine scientific experiment. Unless the innovation is disastrously misconceived, or the introduction is so hamhanded that the students abreact, the exam results at the end of the course will always be better. There was a beautiful example of this reported long ago by the Newcastle ECG department. Those involved introduced new teaching methods, but (being good scientists) used controls: half the class were taught by the old method. The trial group did strikingly better than previous years, but so did the controls though not quite as much (Stretton, Hall & Owen, 1967). Merely the sense of something happening, that teachers are taking their teaching more seriously than usual, is enough to stir students up to greater efforts. This does not mean that innovations should not be reported. If an investigator has a genuinely new idea in medical teaching, and has tried it in practice and it works, it ought to be published. It need not involve technical virtuosity: if a teacher is teaching embryo surgeons to operate on holographic images, well and good, but new methods of persuading students to take an interest in the less favoured areas of their own countries’ diverse communities can be just as important. If the new idea is genuinely new, and important enough to be worth considering by other medical schools, it may well deserve publishing. The examination results may be worth including in the paper, but (no matter how elaborate the statistics) they are very little value as evidence and never worth more than a few lines of print. If an investigator wants to prove from examination results that the technique is a genuine advance, he needs to show that the improvement is steadily maintained for at least 3 years: it would be better still if tried in more than one school. There are all sorts of collateral evidence that could be sought: Is the improvement in performance in the subject reflected in related subjects later in the curriculum? Has it increased the willingness of students to take up an unpopular specialty after qualifying? Has extra time taken affected the staffs research output? There are all sorts of ways of widening the view beyond the single exam. The main thing, of course, is to combine good students and good teachers in a lively, well-organized medical school. But without innovations in teaching, no school remains lively. Innovate, yes, but publish?—yes, sometimes, but however good the idea, do not imagine that anything can be proved by statistics if the Hawthorne effect is neglected.

The genetic aspects of infantile cortical hyperostosis are discussed. A pedigree is presented, based on the history and clinical and radiological investigations of all living members of the family, with data from 11 cases with the condition in two generations, and one possible case from a third generation. The data suggest that an autosomal dominant gene with varying expressivity could be responsible in this family and, though the genetic outlook is unfavourable, it is fully balanced by the benign character of the disease. A chronic form of infantile cortical hyperostosis affecting 2 girls and 1 boy in the family is described with a follow-up of 3 to 5 years. There was no deterioration in the general state of health of the patients and no abnormality was detected in laboratory investigations. At the end of the second year of life, curving of the long bones was usually present radiologically and the appositionless corticalis was paper thin with extended marrow cavity. With increasing age the bowing of the bones became less noticeable (but can be permanent in some cases), the corticalis thickened, while marrow cavity volume decreased. In the marrow cavities the remains of insufficiently resorbed original hyperostoses were seen. All the affected bones exhibited both numerous Park's stress lines and osteoporosis, more marked in the bones of the lower extremities. Even these changes disappeared with increasing age. Neither the metaphyses nor epiphyseal ossification centres were affected by the condition.